Reference is made to an article by one of us entitled "Six (6) Easy Enhancements of Continuous Pin And Post Terminals", delivered at the Sept. 25-28, 1989 Coil Winding Proceedings Meeting at O'Hare Exposition Center, Rosemont, Ill., whose contents are herein incorporated by reference. This article describes state-of-the-art insertion machines for inserting into a PCB square, rectangular or round pins from a continuous supply of pre-notched, pre-starred pin material wound on a reel. These mounted pins, connected to the printed circuits, are used via female connectors for making external connections to the circuits on the PCB. The article also describes machine inserting into the PCB pin headers containing one or two rows of standard-spaced pins for receiving a multi-hole connector. With the increasing popularity of surface mounting of components, the article shows in FIG. 6 how to machine surface mount header-supported pins, with the header assuring the critical pin pitch uniformity for proper mating with the female connector. The pins are secured in place by bonding to the solder pads on the substrate, i.e., the surface of the PCB.
A popular technique to populate PCBs with components is to use a pick and place machine. The pick and place machine is typically provided with components seated in pockets in a plastic tape supplied from a reel, with the machine using a vacuum or suction head to pick a component from a pocket and place it, as directed by a computer, into its proper location on the PCB.
Attempts to use such standard machines to also pick and place header-supported pins has not, to our knowledge, been successful. A problem is that the same suction head that picks and places components, such a resistors, capacitors, and transistors or ICs, can not reliably pick up the header-supported pins. It is possible to build a machine that uses grippers, not suction, to pick and place header-supported pins, but then assembly costs would increase if two machines are needed to pick up suction and gripper placed components. Moreover, grippers may damage individual pins.
The common way of circumventing the problem is by hand mounting in the following manner. The portion of the pin below the plastic header is bent in alternating gull wing shape. In other words, if there were a four position SMT (surface mount technology) pin header, then the bottom portion of the first pin would be bent at 90 degrees to the left, the second pin would be bent at 90 degrees to the right, etc. This, is the common way of surface mounting pin headers to a board. This, of course, is more costly than machine mounting. Moreover, using a header to support and position the pins results in an assembly that when mounted makes for a higher profile when mated with a female connector. This can be undesirable for small packages. In addition, alternating bends use more space on a PCB.